Field of the Invention
The present disclosure relates to the field of dampening devices for vehicles, such as bicycles, motorcycles and four or greater wheeled vehicles. In a further aspect, the disclosure relates to fluid dampers having lower incidence of cavitation and predictable and user variable, separate, compression and rebound characteristics.
Description of Related Art
Vehicle suspension systems typically include a spring component or components and a damping component or components. Typically, mechanical springs, such as metal leaf or helical springs, have been used in conjunction with some type of viscous fluid based damping mechanism mounted functionally in parallel. Dampers commonly include a housing forming a generally fixed volume chamber having a piston therein, which is attached to a suspension component by a rod or shaft attached thereto and extending from the chamber, and which piston moves axially within the chamber to dampen the impact of a suspension force event, such as a bump or obstruction in terrain over which the vehicle is moving. The damper typically operates by restricting the flow of working fluid across or through the piston as it traverses the chamber to slow the movement of a piston therein, especially during a compression stroke. The fluid flow restriction elements, because they are located on the piston which is sealed within the housing, are typically not user adjustable, and are also typically preset for “average” use conditions and thus are not adaptable to varying conditions.
One variant of the above described damper construct employs a gas reservoir which is coupled to the fluid of the damper across a floating piston. The gas reservoir provides a pressure reservoir source which is useful to cause the piston in the damper chamber to return to a steady state position after a compression event, also known as rebounding. During a compression event, the physical size of the fluid volume on the rebound side of the piston may rapidly increase, and if the fluid flow rate into the rebound chamber is not sufficiently fast, the pressure will drop in the fluid on the rebound side of the chamber to a level where any gas, such as air, entrained in the fluid will aspirate to reform a gas state thereof, causing cavitation in the fluid. This can cause serious disruption in the proper operation of the damper, and unacceptable noise emanating from the damper.